Odor memory: Taking stock.

Abstract

This review discusses the state of knowledge in odor memory within the framework of mainstream memory research. Experimental findings are structured around prevailing theoretical distinctions in the study of memory proper, including semantic-episodic memory and implicit-explicit memory. Unaided odor-identification performance is found to be approximately 40%-50% of the total stimulus set presented to Ss, although performance approaches the limit of memorial discrimination if Ss are given label training with feedback. Odor identification is conceptualized as a task with 3 major components and where performance falls on a continuum ranging from nonverbal feelings of familiarity to specific object names. Odor recognition is shown to be relatively stable over long retention intervals, and more than 1 explanation can account for this effect. It is also suggested that name recognition may contribute to the results obtained in odor-recognition experiments. Several possible avenues for future research on both explicit and implicit memory for odors are mentioned. It is concluded that although much is known already about memory for odors, many questions still remain unanswered or unasked.

Odor recognition without identification

“…Although our primary interest in the present study was in odors that could not be identified at test, it is important to first consider how often the participants were able to identify the odors at test. As can be seen in Table 1, identification of the scents at test was fairly difficult, which is consistent with reports in the literature that naming scents is more difficult than naming other types of stimuli (e.g., Cain, 1979;Herz & Engen, 1996;Schab, 1991;Stevenson et al, 2007). Despite this overall difficulty in naming scents, a 2 (study status: studied vs. nonstudied) 2 (study condition: name only vs. name plus scent) mixed model ANOVA performed on the proportion of scents identified revealed a main effect of study status such that more test scents were identified overall when either their names or their names and the scents themselves were studied [F(1,66) Just as identifying word fragments or rapidly flashed and masked stimuli might be considered implicit memory tasks (e.g., Roediger & McDermott, 1993), so might identifying scents.…”

“…Although some prior research suggests that odor imagery involves representations of the actual odors themselves (e.g., Djordjevic, Zatorre, Petrides, & Jones-Gotman, 2004), Stevenson et al demonstrated that names more easily induced imagery of their visual referents (e.g., an image of a strawberry) than of their odor referents (e.g., the imagined smell of a strawberry). Furthermore, in line with prior research (see Herz & Engen, 1996, or Schab, 1991, for a review), Stevenson et al demonstrated that whereas visual images (e.g., an image of a strawberry) are easily named, odors (e.g., the smell of strawberry) are not as easily named.…”

“…In light of this apparent paradox, the present study raises the question of whether the ability to recognize odors that cannot be identified, or the "tip-of-the-nose" effect (e.g., Lawless & Engen, 1977;Schab, 1991), is due to a mere feeling of familiarity with an unidentifiable odor or whether it is an episodic recollection of a prior occurrence with that odor in the face of an inability to identify the odor itself. Future research might aim to determine whether unidentifiable but highly familiar odors (e.g., strawberry, leather) are effective cues for episodic or autobiographical recollections, despite being unnameable, or whether unidentifiable familiar odors are poor cues for episodic recollections but effective triggers of feelings of familiarity.…”

“…Researchers have long known that odors are more difficult to name than visual images or other types of stimuli (e.g., Herz & Engen, 1996;Schab, 1991). Stevenson et al report findings suggesting that the reverse is also true: It is more difficult to imagine an odor (e.g., the smell of strawberry) in response to its name than to imagine what the source of the odor looks like (e.g., a visual image of a strawberry) in response to its name.…”

“…Cleary and Specker presented names of celebrities at study. At test, participants were presented with pictures of celebrities' that the feeling of recognizing an odor without identifying it (sometimes termed the "tip of the nose" experience; Herz & Engen, 1996;Lawless & Engen, 1977;Schab, 1991) is simply the standard tip-of-the-tongue (TOT) experience. In a TOT experience, a person has a feeling of knowing that a word is in memory, despite an inability to access the word at that moment (e.g., Brown, 1991;Gollan & Brown, 2006;Rastle & Burke, 1996;Schwartz, 2002).…”